All Ductile Iron fittings are tested at the following test pressure as specified in ISO : 2531 / BSEN: 545/1995 AND IS : 9523.

For hydrostatic test, the fittings are kept under pressure for 10 seconds. They withstand the pressure test without showing any sign of leakage, sweating or other defect of any kind. The test is conducted before the application of surface coating.

Diameter mm

Works Test Pressure (kg/cm2)

80-300

25

350-600

16

700-1200

10

900-1200

10

Dimensions of Push-on and Mechanical Joint Fittings

External Diameter DE (mm)

Wall Thickness, DE (mm)

DN

Nominal

Tolerance

K12

Tolerance

80

98

+1/-2.7

7.0

-2.38

100

118

+1/-2.8

7.2

-2.40

125

144

+1/-2.8

7.5

-2.42

150

170

+1/-2.9

7.8

-2.45

200

222

+1/-3.0

8.4

-2.50

250

274

+1/-3.1

9.0

-2.55

300

326

+1/-3.3

9.6

-2.60

350

378

+1/-3.4

10.2

-2.65

400

429

+1/-3.5

10.8

-2.70

450

480

+1/-3.6

11.4

-2.75

500

532

+1/-3.8

12.0

-2.80

600

635

+1/-4.0

13.2

-2.90

700

738

+1/-4.3

14.4

-3.0

750

790

+1/-4.4

15.0

-3.05

800

842

+1/-4.5

15.6

-3.10

900

945

+1/-4.8

16.8

-3.20

1000

1048

+1/-5.0

18.0

-3.30

1100

1152

+1/-5.4

19.2

-3.4

It may appear that the test pressure for fittings are low compared to the allowable working pressures in pipes. But fittings with K12 thickness of ductile iron cannot burst at allowable working pressures of pipes.

Due to practical difficulties, fittings are not tested at the factory to very high pressures. BS : 8010 Section 2.1 British Standard Code of Practice for Pipeline Part 2 (Section 2.1 - Ductile Iron) Clause 13 says, “Practical considerations limit the works hydrostatic test pressure to values which may be lower than the site test pressure". The same comment is mentioned in IS : 9523/2000 also. The above pressures are sufficient to detect any casting flaw. After the pipeline is laid and fittings are in position and provided with proper anchorage, the entire pipeline can be pressure tested at a much higher pressure than the works test pressure.